The present invention relates to an RFIC tag attached to a metal object and a method of using the RFIC tag.
Recently, an RFIC (Radio Frequency Integrated Circuit) system is widely used where data is communicated via a radio wave between an RFIC tag, which contains an IC chip activated by a radio wave, and a reader, a writer, or a reader/writer (hereinafter generically called a reader/writer). Because this RFIC system uses an antenna, provided both on an RFIC tag and a reader/writer, for data communication to allow data to be communicated even if the RFIC tag is away from the reader/writer and because an RFIC tag is resistant to stain, the system finds various applications in production management in a factory, physical distribution management, room entry/exit management, and so on.
An RFIC tag having a dipole antenna and operating in the UHF band or SHF band does not work when it is placed near to a metal, for example, when it is placed directly on a metal object. Therefore, when an RFIC tag is attached to a metal object, a spacer made of plastic or rubber is provided between an RFIC tag and a metal object to keep spacing between the metal object and the antenna for suppressing the effect of the metal.
However, the problem is that, if a thinner spacer is used to narrow the spacing between the surface of the metal object and the antenna, the RFIC does not work. On the other hand, if a thick spacer is used to increase the spacing between the metal object and the antenna, the communication distance is extended but the RFIC tag protrudes from the surface of the metal object and, in this case, there is a possibility that the metal object, when used, strikes against a surrounding object or against another metal object with the result that the RFIC tag is damaged.
To solve the problem, JP-A-2005-309811 (see FIG. 2, FIG. 4, FIG. 6, and FIG. 7) discloses an RFIC tag in which a soft magnetic material is provided on the mounting face of the metal object on which the dipole antenna is attached, or a soft magnetic material and a spacer are provided from the metal object side on the mounting face of the metal object on which the dipole antenna is attached, or a spacer, a soft magnetic material, and a spacer are provided from the metal object side on the mounting face of the metal object on which the dipole antenna is attached.